Amylase is an enzyme responsible for breaking down the main source of carbohydrates in the human diet, namely, starch. The digestion of starch begins in the mouth where alpha-amylase present in saliva hydrolyzes glucosidic bonds of starch. By the time thoroughly chewed food reaches the stomach, the average chain length of starch is reduced from several thousand to less than eight glucose units. The acid level in the stomach inactivates the salivary alpha-amylase. Further digestion of starch continues in the small intestine by pancreatic alpha-amylase, which is similar to salivary alpha-amylase.
Decreasing the absorption of carbohydrates by inhibiting the digestion of starch is a very promising strategy in the fields of, for example, weight loss and diabetes mellitus. From a dietary standpoint, it is important to target the breakdown of starch since starch is a relatively non-essential nutrient, which provides calories with little benefit.
Amylase inhibitors are derived from various sources, including vegetable albumins and leguminous plants. Currently, extracts from beans are being utilized most often as a source of amylase inhibitors.
Current methods for purification of amylase inhibitors, which include concentrating and drying beans, include the use of heat treatments and/or solvents. See, for example, U.S. Pat. No. 6,340,699, Cestaro et al, issued Jan. 22, 2002. However, the use of heat treatments and/or solvents has several drawbacks. For example, at high temperatures, certain heat sensitive components of the amylase inhibitor from beans can become degraded. As a result, the amylase inhibitor exhibits a decrease in both stability and potency. In addition, there can be environmental and health concerns associated with the use of solvents during such purification processes. For example, extraction of amylase inhibitors from beans using solvents can result in residual contamination of the extract with the toxic solvent. Furthermore, disposal of the large quantities of solvent required during purification processes can raise environmental concerns.
Examples of such amylase inhibitor purification processes are as follows:
U.S. Pat. No. 6,340,669, Cestaro et al (assigned to Hunza di Maria Carmela Marazzita S.A.S.), issued Jan. 22, 2002, describes lipoprotein complexes which comprise an amylase-inhibiting protein together with a phospholipid (such as phosphatidylcholine). These complexes are said to be useful in treating hypercholesterolemia.
U.S. Published Patent Application 2006/0147565, Skop et al (assigned to Pharmachem Laboratories, Inc.), published Jul. 6, 2006, describes the extraction and purification of amylase inhibitors from white beans using supercritical carbon dioxide processes under vacuum pressure. A method for inducing weight loss using the purified amylase inhibitors is also taught.
U.S. Published Patent Application 2009/0042779, Bollini et al, published Feb. 12, 2009, defines the use of beans, which are bred to be essentially free from phytohemagglutinin, for extracting amylase inhibitors, as well as the combination of that extract with phaseolamin. The described highly purified phaseolamin extract is said to be safe and suitable for consumption by man and animals.
U.S. Published Patent Application 2009/0169657, Berlanda et al, published Jul. 2, 2009, describes the use of hydro-ethanolic mixtures on suitably concentrated aqueous extracts of kidney beans to produce enriched extracts with an alpha-amylase inhibitor content having an activity between 1,000 and 1,600 USP/mg and a phytohaemagglutinin content between 8,000 and 30,000 HAU/g. It is said that this extract can be formulated for diet use at relatively low doses.
In the mouth, alpha-amylase begins the process of the enzymatic digestion of starch, a main source of carbohydrates in the human diet. Proteinaceous amylase inhibitors from Phaseolus vulgaris (white kidney bean) varieties have been known for some time. Decreasing the absorption of carbohydrates by blocking starch digestion through the inhibition of amylase can aid in the control of weight gain or diabetes mellitus. To achieve this end, methods have been developed to extract amylase inhibitors from beans in order to allow the incorporation of said inhibitors into dietary supplements. Current methods for the extraction and purification of amylase inhibitors from beans have not been totally satisfactory in terms of processes that involve harsh heat and solvent treatments which yield amylase inhibitors having impurities and/or less than full activity. U.S. Published Patent Application 2006/0147565, discussed above, describes a process for purifying the amylase inhibitor from white kidney beans that is claimed to be more potent than the amylase inhibitors derived from conventional methods employing heat and solvents. Surprisingly, it has been discovered that the amylase inhibitor extract powder as processed by the methods described in the '565 patent application can be further improved by an additional process step. The result is a clear, stable, tasteless aqueous mixture which contains the amylase inhibiting protein having a significant increase (as much as tenfold) in activity.